This application is based on application No. 2000-209998 filed in Japan.
1. Field of the Invention
The present invention relates to a projector for projecting images.
2. Description of the Background Art
A projector utilizing liquid crystal panels controls these panels based on image signals, and guides light from a lamp to the panels and then to the screen, thereby projecting images on the screen. The lamp used in such a projector has high intensity because images formed on the liquid crystal panels are projected as magnified images by using an optical system. Being irradiated in a high illumination, the liquid crystal panels get hot. The liquid crystal panels realize image display by partly shielding the light from the lamp using a polarizer, so that the vicinity of the polarizer gets hot in particular.
It has been conventionally conducted to cool the liquid crystal panels by supplying the panels with a current of air from a cooling fan.
However, the fan makes untoward noises. Since the recent projectors use a fan having a high blowing capability in keeping with the high intensity of the lamp, the fan makes more noises.
In the case of a rear-projection type television system with a projector, the cooling fan is stored in a large casing and used in an ordinary household, so that the noise reduction of the fan is an important issue.
According to the present invention, a projector comprising: a light source; an optical system for guiding light from the light source to an projective region; a display device for modulating the light from the light source, based on image signals, the display device being arranged in a light path of the optical system; at least one fan for cooling the display device; and a fan controller for receiving signals based on the image signals and varying a number of revolutions of the at least one fan in accordance with changes in the image signals.
Thus, in the projector, the number of revolutions of at least one fan is varied in accordance with changes in the image signals, which makes it possible to reduce unnecessary noise caused by the fan.
In an aspect of the present invention, the fan controller receives signals based on voice signals, and changes the number of revolutions of the at least one fan in accordance with changes in the voice signals.
Thus, in the projector, the number of revolutions of at least one fan is varied in accordance with changes in the voice signals, which makes it possible to reduce untoward noises caused by the fan.
In another aspect of the present invention, while changing the number of revolutions of the at least one fan, the fan controller provides fluctuations to the numbers of revolutions.
Thus, the number of revolutions of at least one fan is given fluctuations, which makes it possible to reduce untoward noises caused by the fan.
In another aspect of the present invention, the projector further comprises a memory for storing data concerning cumulative amount of lighting time of the light source, wherein the fan controller reduces the number of revolutions of the at least one fan, as the cumulative amount of lighting time becomes larger.
Thus, the noises caused by the fan can be reduced in accordance with a decrease in intensity of the light source.
In another aspect of the present invention, the display device has a plurality of component devices corresponding to a plurality of colored lights; the at least one fan includes a plurality of fans arranged separately in correspondence with the plurality of component devices so as to cool the plurality of component devices separately; and the fan controller controls the number of revolutions of the plurality of fans separately, based on the image signals corresponding to the plurality of colored lights.
Thus, in the projector, a plurality of fans can be individually controlled.
In further another aspect of the present invention, the display device is a single device for displaying images based on color image information; the at least one fan is a single fan for cooling the single device; and the fan controller changes the number of revolutions of the single fan in accordance with changes of G and B color components contained in the image signals.
Thus, in the projector, the control of the fan can be simplified.
According to the present invention, a projector comprising: a screen; a main-body casing which forms the outside shape of the projector and in which the screen is installed; a light source; an optical system for guiding light from the light source to the screen; a display device for modulating the light from the light source, based on image signals, the display device being arranged in a light path of the optical system; at least one fan for cooling the display device; and a fan controller for receiving signals based on the image signals and varying a number of revolutions of the at least one fan in accordance with changes in the image signals.
Therefore, noises can be reduced in the case with a screen and a main-body casing additionally provided.
Thus, the object of the present invention is to realize a reduction in noise (including substantial noise reduction of eliminating grating noise) caused by the cooling fan in a projector.
These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.